Method for preventing total failure of a processing unit for protocol information

ABSTRACT

The invention relates to a method for preventing total failure in a processing unit for sending and receiving protocol information for a large number of transmission channels, wherein a protocol process is started by a controller for every protocol and a separate monitoring process that monitors the orderly time duration of the protocol process can be activated or deactivated parallel thereto for every protocol process. If the previously determined time duration of the protocol process is exceeded, the monitoring process reports it to the controller, whereupon the controller stores relevant data for subsequent localization of errors.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US National Stage of International ApplicationNo. PCT/DE02/04500, filed Dec. 6, 2002 and claims the benefit thereof.The International Application claims the benefits of German applicationNo. 10161295.8 filed Dec. 13, 2001, both of the applications areincorporated by reference herein in their entirety.

FIELD OF INVENTION

The invention relates to a method for preventing total failure in aprocessing unit for sending and receiving protocol information and aprocessing unit for sending and receiving protocol information.

BACKGROUND OF INVENTION

The general background to the present invention is a processing unit,which sends and receives the information required by a protocol (e.g.SSCOP, #7, HDLC, internal transport protocol, etc.). Such processingunits are integrated in many networks, to allow the transfer of datawithin the network.

Technical developments mean that the requirements relating to processingunits are ever more stringent. For example protocol information has tobe sent and received in increasingly short time units. This can beachieved on the one hand by minimizing the time required for atransmission operation and on the other hand by increasing the number oftransmission channels.

To minimize the time required for a transmission operation, the protocolinformation is transported using high-performance switching technology,e.g. Asynchronous Transfer Mode (ATM).

Increasing the number of transmission channels in a processing unit forsending and receiving protocol information (currently approx. 16000)gives rise in some instances to management problems, as it is virtuallyimpossible to support a corresponding number of transmission channels inthe conventional manner.

In order to be able to support all channels, the protocol must be set upin the hardware, for example via an ASIC (Application SpecificIntegrated Circuit) and/or an FPGA (Field Programmable Gate Array).

ASICs are special chips, which are designed and optimized on thestrength of specific deployment, to achieve a high level of performance.

To optimize the circuit design of said chips, the trend in recent yearshas moved away from the conventional digital circuit design withstandard logic (74xx) to programmable logic. FPGA in particular hasgained in significance as a result.

ATM and ASIC have been combined for the transmission of informationsince the end of the nineties. The combination is used successfully forexample in the digital telephone switching system EWSD (ElectronicWorldwide Switch Digital).

During the transmission of information what is known as a work splitdefines which part of the protocol is processed by the ASIC and whichpart of the protocol is processed by the subsequent software in theprocessor on the assembly.

Networks are generally tested before the actual transmission of usefuldata. It is however not possible due to the complexity of the protocolsto test the processing of all situations beforehand. A certain errorprobability therefore always remains. This can mean that in somecircumstances defective protocol information is received, which resultsin total failure of the system. The other transmission channels arethereby also affected.

If an error occurs in an ASIC, the following problems can potentiallyoccur during error correction:

error location is extremely difficult in a complex ASIC,

immediate error rectification is not possible or is only possible byredesign, and

protocol processing can only be restarted by resetting the hardware.

There is therefore a need for a method, which prevents total failure(deadlock) during protocol processing.

SUMMARY OF INVENTION

The object of the invention is therefore to develop a method, whichprevents total failure during protocol processing.

This object is achieved according to the invention by the features ofthe independent Claims. The dependent Claims develop the central idea ofthe invention in a particularly advantageous manner.

The central concept of the invention is to achieve a method forpreventing total failure in a processing unit for sending and receivingprotocol information for a large number of transmission channels in thata protocol process is started by a controller for every protocol andparallel to this for every protocol process a separate monitoringprocess can be activated, which is started at the same time as theprotocol process and monitors the time duration of the protocol processto identify a defective transmission channel.

It is also necessary for it to be possible for the software to activateand deactivate the monitoring process separately for every protocolprocess.

The monitoring process advantageously reports to the controller if aspreviously defined time duration of the protocol process is exceeded. Ifit is, it must be assumed that the protocol information is defective,putting protocol processing in a “deadlock” state.

It is particularly advantageous, if the duration of the monitoringprocess can be adjusted separately for every protocol process, as thedifferent processes require different times. Alternatively the durationof all monitoring processes can be defined as the maximum possibleprocess duration. This however results in an unnecessary time delay inthe identification of defective protocol information.

A time base, which predefines a basic clock rate, is integrated in theprocessing unit to control the time duration of the monitoring process.

According to the invention the controller secures the data relevant tothe subsequent error location, as soon as it receives a report from themonitoring process that the duration of the protocol process isexceeding the previously defined time. The relevant data includes thename of the protocol process, the current state of the protocol processand/or further signal states. It is stored in registers.

The controller then resets the processing unit, whereby the data, whichis stored for subsequent error location, is retained.

After the reset operation the controller starts a process, which readsthe last received message triggering the error response from the receivestorage device and forwards it together with the stored data for errorlocation to external software.

The processing unit is then ready to process the next message and totalfailure does not result.

The defective transmission channel of the processing unit is alsoblocked and can only be released by the software after successful errorrectification.

BRIEF DESCRIPTION OF THE DRAWING

One example of the sequence for processing protocol informationaccording to the invention is described below with reference to FIG. 1.

DETAILED DESCRIPTION OF INVENTION

The protocol information is transmitted for example in ATM cells to aprocessing unit 1. There is therefore a hardware unit on the receiveside of the processing unit 1 for processing the received protocolinformation. In the present case this is an RA (Receive ATM AdaptationLayer).

The received protocol information is buffered in a receive storagedevice 5. The storage device manager sends a signal 14 to the controller2 that information has to be processed. The controller then decides onthe basis of a control word (protocol mode) which protocol 3 saidmessage is intended for. Every protocol 3 has a specific process, whichis started by the controller 2 by means of a start signal 15. Theprotocol process 3 a processes the information and then transmits allthe relevant data via a signal 13 to a bus interface 6, which in turnforwards it via a signal 12 to subsequent software in the processor onthe assembly for further processing.

To monitor the time of the protocol process 3 a, a monitoring process 4a is started parallel to this and at the same time in a monitoring unit4 by means of a start signal 17. The maximum permitted duration of themonitoring process is determined individually for every protocol process4 a. For the purposes of time optimization, it is determined as the timerequired by the protocol process 3 a for error-free processing. Tocontrol the duration of the monitoring period, the monitoring process 4a obtains a basic clock rate 18 from a time base 7.

When the protocol process 3 a terminates its work stages, it signalsthis to the controller 2, which then stops the monitoring process 4 a.It is therefore essential that every monitoring process 4 a can bedeactivated separately. The storage device manager of the receivestorage device 5 is then informed that the information has beenprocessed and the next message can therefore be processed.

If the monitoring process 4 a is terminated before the protocol process3 a is terminated, it must be assumed that the protocol information isdefective, thereby putting protocol processing in a “deadlock” state.

In this case the monitoring process 4 a reports the existence ofdefective protocol information to the controller 2 by means of an errornotification 19. The controller 2 then secures all relevant data, suchas the name of the protocol process that caused the error, the currentstate of the protocol process to locate the cause of the error and/orfurther signal states as a function of the respective protocol inregisters.

The controller 2 then resets the entire unit, whereby the data storedfor subsequent error location is retained. The protocol process 3 a, themonitoring unit 4, the time base 7 and the bus interface are therebyreset. This can be achieved for example in that the reset signal 10 isgenerated by an OR circuit 9, to which the output signal 111 of thecontroller 2 and the external reset signal 8 are fed.

After the reset operation, the controller 2 starts a process, whichreads the last received message triggering the error response from thereceive storage device 5 via a signal 16 and forwards it together withthe stored data for error location to the external software 20.

A signal is then sent to the storage device manager of the receivestorage device 5 that the information has been processed and the nextmessage can be processed.

The defective transmission channel is also immediately blocked by thesoftware 20 or the hardware and can only be released again by thesoftware 20 after successful error rectification.

The invention therefore allows total failure to be prevented in aprocessing unit in the event of defective protocol information and thecause of the error to be determined.

1. A method for preventing a deadlock failure in a processing unit thatsends and receives protocol information for a plurality of transmissionchannels, comprising: receiving a message having a protocol; starting aprotocol process by a controller, the protocol process adapted forprocessing the protocol information in the message; starting a separatemonitoring process when starting the protocol process, the monitoringprocess having a time duration and also associated with the protocolprocess, the time duration of the monitoring process being at least theamount of time required by the protocol process for a deadlock-freeprocessing of the protocol information; and notifying the controller bythe monitoring process of the deadlock failure when the monitoringprocess has not been terminated via the controller after exceeding thetime duration, wherein the deadlock failure is used to indicate that theprotocol information in the received message is defective.
 2. The methodaccording to claim 1, further comprising: terminating the protocolprocess after completing the processing of the protocol information;informing the controller of the termination of the protocol process; andterminating the associated monitoring process, wherein the protocolprocess is terminated prior to the time duration of the associatedmonitoring process.
 3. The method according to claim 2, wherein the timeduration of the monitoring process is measured on the basis of a basicclock rate predefined by a time base.
 4. The method according to claim2, further comprising storing relevant data for a subsequent failureprocessing by the controller in response to a receipt of the failurenotification.
 5. The method according to claim 4, wherein the relevantdata comprises the name of the protocol process, the current state ofthe protocol process and/or further signal states.
 6. The methodaccording to claim 5, wherein the controller resets the processing unit,whereby the data stored for subsequent failure processing is retained.7. The method according to claim 6, wherein after the reset operationthe controller starts a process that reads the last received messagetriggering the failure response from the receive data storage unit andforwards it together with the stored data for error location to anexternal software program.
 8. The method according to claim 7, whereinthe defective transmission channel is immediately blocked.
 9. The methodaccording to claim 8, wherein the external software program unblocks thedefective transmission channel after successful error rectification. 10.A processing unit for sending and receiving protocol information for alarge number of transmission channels, comprising: a controller thatstarts a protocol process for every protocol, the protocol processadapted to process protocol information; and a monitoring processactivated for each started protocol process such that each startedprotocol process has an associated monitoring process, wherein themonitoring process monitors the time duration of the protocol process,the time duration being at least the amount of time required by theprotocol process for a deadlock-free processing of the protocolinformation, and wherein a defective protocol error is detected if theprotocol process has not processed the protocol information within theduration time.
 11. The processing unit according to claim 10, furthercomprising a time base which predefines a basic clock rate that the timeduration of the monitoring process is measured.
 12. The processing unitaccording to claim 10, wherein the monitoring sends an errornotification message to the contoller after the error is detected. 13.The processing unit according to claim 10, wherein upon receipt of themessage the controller stores relevant data for subsequent errorlocation in a register.
 14. The processing unit according to claim 13,wherein the controller resets the processing unit, whereby the datastored for subsequent error location is retained.
 15. The processingunit according to claim 14, wherein after the reset operation thecontroller starts a process that reads the last received messagetriggering an error response from the receive storage device andforwards it together with the stored data via a bus interface for errorlocation to an external software program.
 16. The processing unitaccording to claim 15, wherein the controller is connected to theexternal reset signal via an OR circuit.
 17. The processing unitaccording to claim 16, wherein the defective transmission channel isblocked by the external software program.
 18. The processing unitaccording to claim 17, wherein the external software program releasesthe defective transmission channel after error rectification.
 19. Amethod for avoiding a deadlock failure in a processing unit that sendsand receives protocol information for a plurality of transmissionchannels, comprising: receiving a message having a protocol; starting aprotocol process by a controller, the protocol process adapted forprocessing the protocol information in the message; starting amonitoring process associated to the protocol process processes, themonitoring process having a duration time related to the protocol of theassociated protocol process, the monitoring process started when theassociated protocol process started; after completing the processing ofthe protocol information: terminating the protocol process, informingthe controller of the termination of the protocol process, andterminating the associated monitoring process; and after exceeding thetime duration: notifying the controller by the monitoring process of anerror after exceeding the time duration, the error is used to indicatethat the protocol information is defective, wherein the deadlock failureis used to indicate that the protocol information in the receivedmessage is defective.
 20. The method according to claim 19, furthercomprising: saving information pertaining to the received message;blocking a transmission channel having sent the received message inresponse to the notification; and resetting the processing unit by thecontroller in response to the notification.
 21. The method according toclaim 20, further comprising: starting a process to read the savedinformation after the resetting; and forwarding the read information toan external program.